Supply device for supplying an electronic circuit

ABSTRACT

A device for supplying an electronic circuit with a dock signal having a dock frequency includes a frequency actuator that generates the dock signal in accordance with a frequency setting according to a regulation mechanism. A control module selectively applies to the frequency actuator a first frequency setting or a second frequency setting that is higher than the first setting. An adaptation module modifies the regulation mechanism in accordance with the applied setting

RELATED APPLICATION

This application is a U.S. nationalization of PCT Appl. No. PCT/FR2013/051433, filed Jun. 19, 2013, and published as PCT publication No. WO 2013/190236 on Dec. 27, 2013.

TECHNICAL FIELD

The invention concerns a supply device for supplying an electronic circuit with application of a clock signal.

BACKGROUND

When it is desired to minimize the energy consumption of a synchronous digital electronic circuit for which timing is provided by a clock signal, while maintaining its performance, it is known to apply to that circuit a clock frequency adapted to a given supply voltage. By “synchronous circuit” is meant a “circuit for which timing is provided by a clock”.

It has moreover been proposed to adapt the clock frequency according to the performance desired for the system, and also to modify the supply voltage, a technique known under the acronym DVFS (for “Dynamic Voltage and Frequency Scaling”).

These techniques are applied in particular in the case of GALS architectures (GALS standing for “Globally asynchronous Locally Synchronous”), in which the system concerned is divided into different VFIs (VFI standing for “Voltage Frequency Island”). Such architectures are for example produced in the form of SoCs (SoC standing for “System on Chip”).

The variable supply voltage to apply to an electronic circuit is generated by a module named “voltage actuator”, for example in accordance with the technique referred to as “Vdd-hopping”, described in the paper “A power supply selector for energy- and area-efficient local dynamic voltage scaling”, by S. Miermont, P. Vivet and M. Renaudin, in Lecture Notes in Computer Science, Volume 4644, pages 556-565, 2007.

As regards the clock signal of variable frequency to apply to the electronic circuit, this is generated by a module referred to as “frequency actuator”; such a frequency actuator is for example produced in the form of an FLL (for “Frequency Locked-Loop”) or in the form of a PLL (for “Phase Locked-Loop”).

Such frequency actuators are produced in the form of a system operating in a closed loop which includes in particular a controller influencing the variable generated according to the measured error (difference between the variable measured and the setting) and according to a control law.

SUMMARY

The invention provides a supply device for supplying an electronic circuit with application of a clock signal having a clock frequency, comprising a frequency actuator designed to generate the clock signal according to a frequency setting using a regulation mechanism, as well as a control module designed to selectively apply to the frequency actuator a first frequency setting or a second frequency setting higher than the first setting characterized by an adaptation module designed to modify the regulation mechanism according to the applied setting.

The regulation mechanism may thus be adapted to the applied setting, which makes it possible to obtain differentiated processing depending on whether the new setting is directed to an increase or a decrease in frequency.

The response time of the frequency actuator may thus be variable according to the sign of the frequency variation imposed by the new setting relative to the former setting.

The adaptation module then enables that response time to be increased or decreased respectively depending on whether the input setting is directed to an increase or a decrease in frequency.

In other words, the adaptation module may modify the regulation mechanism such that the response time of the frequency actuator increases or decreases respectively depending on whether the applied setting increases or decreases.

The response of the frequency actuator is thus differentiated according to the direction of variation of the frequency setting.

The frequency actuator comprises for example a controller receiving an error signal obtained by difference between the frequency setting and a measured frequency of the clock signal. The frequency actuator may also comprise an oscillator controlled by a control signal generated by the controller; the oscillator then for example generates the clock signal in this case.

According to a possibility for an embodiment, the adaptation module may comprise means for determining a gain of the oscillator by measurement of at least one value involved in the regulation mechanism and the adaptation module may then be designed to modify the regulation mechanism according to the determined gain. This makes it possible to adapt the regulation mechanism taking into account in real time the variations in the oscillator gain.

For example, when the controller is designed to apply a gain to the error signal, it can be provided for the adaptation module to be designed to control the gain applied by the controller according to the determined gain.

More generally, it may be provided for the adaptation module to be designed to modify an operating parameter of the controller. This is an effective and generally simple manner of implementation for the purpose of modifying the regulation mechanism.

As already stated, the controller may be designed to apply a gain to the error signal. The adaptation module is for example designed in this case to control the gain applied to the error signal.

In practice, it may be provided for a selector controlled by the adaptation module to be designed to selectively apply the error signal to a multiplier from among a plurality of multipliers.

According to another possibility, which may possibly be combined with the aforementioned gain control, the controller may comprise a memory designed to store a control value and the adaptation module may then be designed to force the memory to a predetermined value on detection of a setting jump. As explained below, this may enable faster convergence towards the setting.

According to a possibility for an embodiment, the device according to the invention may further comprise a voltage actuator designed to generate a voltage according to a voltage setting, adapted to the frequency setting, on application of that frequency setting to the frequency actuator.

The frequency and voltage actuators are thus synchronized.

BRIEF DESCRIPTION OF THE DRAWING

Other features and advantages of the invention will better appear on reading the following description, made with reference to the accompanying drawings in which:

FIG. 1 represents a general context in which the present invention may be implemented;

FIG. 2 represents the main components of a frequency actuator in accordance with the teachings of the invention;

FIG. 3A represents a first example embodiment of the controller of FIG. 2;

FIG. 3B represents a variant embodiment of the first example embodiment;

FIG. 4 represents a second example embodiment of the controller of FIG. 2;

FIG. 5 represents a third example embodiment of the controller of FIG. 2;

FIG. 6 represents a fourth embodiment of the invention.

DETAILED DESCRIPTION

As can be seen in FIG. 1, a supply device 1 for supplying an electronic circuit 8, for example a voltage frequency island (or VFI) of a GALS architecture, comprises a control module 2 which generates a voltage setting V_(set) and a frequency setting F_(set).

These settings are generated according to the desired performance for the electronic circuit 8, for example on the basis of instructions received and a date limit for their execution by an operation coordination module for different islands (not shown).

The voltage setting V_(set) is applied to a voltage actuator 4 which generates, according to the voltage setting V_(set), a voltage V_(appl) applied to the electronic circuit 8.

The frequency setting F_(set) is applied to a frequency actuator 6 which generates a clock signal H at a frequency F_(appl) determined on the basis of the frequency setting F_(set) as explained below. The clock signal H is applied to the electronic circuit 8.

The settings V_(set), F_(set) applied at a given time are such that they enable fault-free operation of the electronic circuit 8.

Thus, in order to pass from a first pair of values (voltage, frequency)₁ to a second pair of values (voltage, frequency)₂, the actions of the voltage and frequency actuators must be synchronized, in particular when the voltage and the frequency are modified within a determined timeslot.

These pairs of values may be determined in advance for a given circuit, for example according to prior investigations carried out on circuits of this type. As a variant, these values may be determined during a calibration phase during which, for each applied voltage, the operation of the circuit is tested for a plurality of envisioned clock frequencies, the highest frequency giving fault-free operation being chosen.

Settings V_(set), F_(set) adapted to fault-free operation are also used when modifications to these settings are made. For example, on a setting change or jump corresponding to a frequency increase, the voltage adapted to the highest frequency encountered during the jump is always applied, then the new frequency is applied once the voltage jump has been made.

The temporal response from the output of a conventional system to a change in setting is however not always adapted to the different situations encountered in operation. Below, “response” means the “temporal response of the output of such a system”.

Thus, for example, the response of the system in closed loop as a whole may be influenced by phenomena such as the variability in the manufacturing process or variations in temperature encountered.

The constraints to comply with by the frequency generated may moreover differ according to the operational phases of the system: in a phase of frequency decrease (new setting less than the prior value), exceedance of the new setting (downwards) can be accepted, whereas such exceedance is unacceptable in the case of an increase in the frequency (new setting greater than the preceding setting) since it could lead to operating faults due to the use of a clock frequency greater than that intended (and for which an adapted voltage is applied to the circuit).

FIG. 2 represents an example embodiment of the frequency actuator 6.

As already indicated, the frequency actuator 6 generates a clock signal H at a frequency F_(appl) on the basis of a frequency setting F_(set).

The frequency actuator 6 comprises a sensor 16 which measures the frequency of the clock signal H and generates a signal representing the measured frequency F_(meas). When the information supplied by the sensor is numerical (that is to say a number), the sensor 16 is typically a counter which produces at its output the number of clock pulses measured in relation to the clock signal H over a predetermined time.

The frequency actuator 6 also comprises a subtracter 10 which determines the disparity (that is to say the difference) between the measured frequency F_(meas) and the frequency setting F_(set) and generates an error signal E representing the computed disparity.

The frequency actuator 6 comprises a controller 12 which receivers the error signal E and which generates, on the basis of that error signal E and according to a control law, a control signal U for the system 14 to control, here a DCO (DCO standing for “Digitally Controlled Oscillator”).

As referred to previously, a disparity or exceedance of the new setting is tolerated when it entails a decrease in frequency, but such an exceedance is unacceptable in the case of a setting entailing an increase in frequency.

The error signal E, in particular its sign, makes it possible to determine whether the exceedance concerned is a decrease or an increase in the frequency, and to provide actions (governed by the control law) to avoid possible operating faults of the circuit 8 due classically to the exceedance of the frequency response of the actuator 6 relative to the setting. The digitally controlled oscillator 14 comprises a digital-analog converter and a VCO (VCO standing for “Voltage Controlled Oscillator”). The digitally controlled oscillator 14 thus generates an output signal of which the frequency is controlled by the control signal U: that output signal is the clock signal H generated by the frequency actuator 6.

The notation K_(DCO) will be used below in relation to the gain of the oscillator 14.

It is to be noted that, in the embodiment described here, the signals representing the different variables F_(meas), F_(set), E and U are digital words and the controller 12 in particular is thus a digital circuit. As a variant, it could naturally be provided that some of the signals, and therefore possibly the controller, be produced in analog form.

FIG. 3A represents a first example embodiment of the controller of 12 of FIG. 2.

In this embodiment, the error signal E is applied selectively to a multiplier (for example that of coefficient K₁ in FIG. 3) from among a plurality of multipliers 34 (here three multipliers with respective coefficients K₁, K₂, K₃) by means of a selector 32 controlled by an adaptation module 30. A version in which the signal E would be applied to all the multipliers 34 and in which the selector 32 controlled by an adaptation module 30 would choose one of the output signals from the multipliers 34 may also be provided, see FIG. 3B.

Returning to the embodiment of FIG. 3A, the output from each multiplier 34 is applied to an adder circuit 36 which also receives as input its own output signal, delayed by a time determined by passage through a memory 38 provided for that purpose.

Such a controller is of integrator type and at the time k generates as output a control signal U(k)=K_(i).E(k)+U(k−1),

where U(k−1) is the control signal at the time (k−1) and K_(i) is the coefficient of the selected multiplier.

It is understood that the value of the parameter K_(i) influences on the time taken by the controller 12 to generate a control signal U which leads to a signal frequency of clock H equal to the setting F_(set) (that is to say a null error signal E), since the value of K_(i) determines the magnitude of the variations in the control signal U at each time according to the formula which has just been given.

A high value of the parameter K_(i) thus leads to a fast variation in the control signal U, which may go as far as an exceedance of the setting (even though the signal will end up converging towards the setting since the exceedance thereof leads to a change in sign of the error signal E).

It is furthermore to be noted that the gain K_(DCO) of the oscillator 14 is variable according to the operating conditions (such as the temperature) and may thus also have an effect on the response time of the looped system (since an error signal E induces a modification K_(i).E of the control signal U and thus a modification K_(KDCO).K_(i).E of the frequency F_(appl) of the clock signal H).

It may be provided for the adaptation module 30 to control the selector 32:

so as to apply the multiplier of coefficient K₁ to the error signal E when the change in setting F_(set) corresponds to a decrease in the desired frequency;

so as to apply the multiplier of coefficient K₂ (with K₂<K₁) when the change in setting F_(set) corresponds to an increase in the desired frequency and when the ambient temperature T is greater (or, according to a possible variant, lower) than a predetermined threshold T₀.

so as to apply the multiplier of coefficient K₃ (with K₃<K₂) to the error signal E when the change in setting F_(set) corresponds to an increase in the desired frequency and when the temperature T is less (or, according to the variant which has just been mentioned, greater) than the predetermined threshold T₀.

The multiplier coefficients K₁, K₂, K₃ are for example predetermined according to the operating values provided for the system. These values may come from an off-line calibration phase or be produced during operation of the system. The use of these coefficients makes it possible to vary the response time of the frequency actuator according to the sign of the frequency variation imposed by the new setting relative to the former setting.

The adaptation module 30 determines the control to apply to the selector 32 for example according to the error signal E (which gives whether the next frequency modification will be a frequency decrease or a frequency increase) and a measurement of the ambient temperature T.

As a variant it could be provided for the adaptation module 30 to determine the control to apply to the selector 32 on the basis of the frequency setting F_(set) applied to the frequency actuator 6. For example, in a system in which two frequency settings are provided (low frequency and high frequency), the adaptation module 30 may control the application of the multiplier K₁ when the setting corresponds to the low frequency and the application of the multiplier K₂ or K₃ (according to the measured temperature T) when the setting corresponds to the high frequency.

FIG. 4 represents a second embodiment of the controller of 12 of FIG. 2.

In this embodiment, the error signal E is applied to a multiplier 44 of coefficient K_(i) (for example fixed). The output of the multiplier 44 is applied to an adder 46 which also receives as input a version which is delayed (using a memory 48) from its output U. /

The memory 48 is for example produced in the form of a register having a predetermined size (for example 8 bits).

The controller also comprises an adaptation module 40 which makes it possible to force the value contained in the memory 48 to a predetermined value, for example when the adaptation module 40 detects a downward change in frequency setting F_(set).

The predetermined value written by the adaptation module 40 on detection of a downward jump in frequency setting may however be variable, according to the new frequency setting: the adaptation module 40 may for example store, in a look-up table, a predetermined value to write in the memory 48 for each of a plurality of ranges of frequency setting value F_(set), or for a set of successive control times subsequent to the jump.

The coefficient K_(i) of the multiplier 44, which is fixed in the example described here, is for example chosen so as to avoid an exceedance of the setting at the time of an upward jump in frequency setting (that is to say that the new frequency setting is greater than the prior frequency setting) in the operating conditions envisioned for the system. It is to be noted that, at the time of such an upward jump in frequency setting, the adaptation module 40 does not act on the memory 48 such that the controller 12 operates so as to make the measured frequency F_(meas) converge towards the frequency setting F_(set) (starting from the actual frequency prior to the frequency jump).

At the time of such an upward jump (or positive jump), the control signal is thus governed as follows: U(k)=K_(i).E(k)+U(k−1).

On the other hand, when the adaptation module 40 detects a downward jump in frequency setting F_(set) (or negative jump, that is to say that the new frequency setting is less than the prior frequency setting), the adaptation module forces the value in memory 48 to a predetermined value U₀ (which depends for example as explained above on the new setting F_(set)).

At the time k following the jump, the control signal U(k) thus has the value: U(k)=K_(i).E(k)+U₀.

The predetermined value U₀ is chosen, for example at the time the system is designed, such that the new control value U(k) leads, after application to the oscillator 14, to a clock having a frequency equal to or less than the new setting F_(set) according to the parameters provided for the operation of the system, in particular the coefficient K_(DCO) already mentioned for the oscillator 14. It is noted that, when the established regime (corresponding to a situation in which the output frequency has attained the setting and no longer changes) was attained before application of the setting change, the value of the error signal E at the time of the jump in principle corresponds at that time to the difference between the new setting and the prior setting.

Naturally, the temporal behavior of the actual frequency generated by the oscillator 14 on account of the control U(k) does not precisely correspond to the temporal behavior expected further to the application of the new frequency setting F_(set), in particular on account of drifts that are present relative to the theoretical operation, and on account of the modification of the value in memory via the adaptation module 40. The actual clock frequency F_(appl) generated by the oscillator 14 will however converge towards the frequency setting F_(cons) on account of the resumption in integrator operation by the controller 12, for example according to the formula U(k+1)=K_(i).E(k+1)+U(k) at the following time (k+1).

It may be specified here in this connection that the adaptation module 40 only forces the value in the memory 48 to the predetermined value U₀ at the time at which the downward setting jump F_(set) is detected. The rest of the time, the memory 48 receivers the value output from the adder 46 as already indicated.

It may be understood that, the predetermined value U₀ being chosen to generate a clock frequency in theory equal to that of the setting F_(set), the actual frequency F_(appl) generated in practice rapidly converges towards the setting F_(set), the response (or convergence) time of the frequency actuator varying accordingly.

Furthermore, it is of no importance that the frequency actually generated on application of the predetermined value U₀ to the memory 48 is greater than or less than the setting F_(set) envisioned since the voltage V_(appl) applied at the time of the jump is as already stated sufficient to ensure error-free operation of the electronic circuit 8 even at frequencies greater than the new frequency setting F_(set). (Typically, the voltage V_(appl) applied at the time of the jump is that previously applied for safe operation with the prior setting, which is greater than the new setting in the case of the downward jump envisioned here.)

FIG. 5 represents a third embodiment of the controller of 12 of FIG. 2.

In this embodiment, the error signal E is applied to a multiplier 54 of coefficient K_(i) which is variable under the control of an adaptation module 50.

The signal output from the multiplier 54 is applied to an adder 56, which also receives as input its own output U delayed using a memory 58.

As previously, the signal U output from the adder 56 is applied to the oscillator 14.

In this embodiment it is provided for the adaptation module 50 to receive both the frequency setting F_(set) and the measured frequency F_(meas).

On detection of a positive setting jump (that is to say an increase in the setting) by the adaptation module 50 (that is to say a variation in the setting F_(set) that it receives), the adaptation module measures the actual convergence time t_(conv) of the frequency towards its setting, that is to say for example the time taken (from the detection of the frequency jump) by the measured frequency signal F_(meas) to f reach the setting, to the nearest given percentage (for example to the nearest 5%).

The adaptation module 50 also determines whether, during the convergence time, the measured frequency F_(meas) goes beyond the new frequency setting F_(cons)

Once the convergence time has been measured and the existence of any exceedance has been determined, the adaptation module 50 modifies the coefficient K_(i) of the multiplier 54 as follows:

if the adaptation module 50 has found the existence of an exceedance of the setting F_(set), the gain K_(i) is rendered by a predefined increment d_(K);

if no exceedance is detected and the convergence time t_(conv) is less than a first predetermined time t₀ (minimum acceptable), the gain is also rendered by a predefined increment, for example the same increment d_(K);

if no exceedance is detected and the convergence time t_(conv) is greater than a second predetermined time t₁ (maximum acceptable), the gain K_(i) is increased by a predefined increment, for example equal to the increment t_(K) already mentioned.

Thus, the value of the gain K_(i) will be continually adapted so as to avoid an exceedance of the frequency setting F_(set) and to obtain a convergence time comprised between the predetermined times t₀ and t₁.

It is to be noted that the procedure which has just been described is applied in the case of a positive jump in setting due to the fact that it is wished to avoid the exceedance of the setting for this type of jump, as already explained.

A similar procedure could also be applied to a negative jump in setting in order to continually adapt the convergence time. The procedure could then be applied after a first modification to the gain K_(i) (in order to use an initial gain adapted to the negative jump) in accordance with the embodiment of FIGS. 3A and 3B.

The frequency response time of the actuator may thus be varied according to the direction of variation of the setting.

FIG. 6 illustrates another embodiment of the invention.

This embodiment is based on a closed-loop architecture as described above with reference to FIG. 2.

In this embodiment, an adaptation module 60 receives the frequency setting values F_(set) and the error values E (already introduced in the context of FIG. 2) and on that basis generates a gain K_(i) which it sends to the controller 12 in order for the latter to apply that gain K_(i) to the error signal E.

The present embodiment is moreover based on an operation of modeling the different blocks by means of a transfer function of z, as represented in FIG. 6.

The closed loop transfer function (that is to say that of the system in FIG. 6 as a whole) is written:

$\mspace{79mu} {\frac{F_{appl}(z)}{F_{set}(z)} = \frac{K_{I}K_{DCO}}{1 - {\left( {1 - {K_{I}K_{DCO}K_{S}}} \right)z^{- 1}}}}$      and $\frac{E(z)}{F_{setting}(z)} = {\frac{1}{1 + \frac{K_{I}K_{DCO}K_{S}}{\left( {z - 1} \right)}} = {\frac{z - 1}{z - \left( {1 - {K_{I}K_{DCO}K_{S}}} \right)} = {\frac{1 - z^{- 1}}{1 - {\left( {1 - {K_{I}K_{DCO}K_{S}}} \right)z^{- 1}}}.}}}$

By denoting E(k) and F_(set)(k) as the values of the error signal E and of the frequency setting F_(set) at the time k, the following temporal expression is obtained for the error e(k):

E(k)=F _(setting)(k)−F _(setting)(k−1)+(1−K _(i) K _(DCO) K _(S))E(k−1).

The case is taken for example in which the system has attained a state of equilibrium at a given time (here denoted k=−1), i.e. E(−1)=0, and in which, at a given time (k=0), the setting is modified stepwise, i.e. F_(set)(0)−F_(set)(−1)=ΔF . We thus have: E(0)=ΔF.

At the following time (k=1), we have F _(set)(1)−F _(set)(0)=0 (on account of the step form of the setting) and:

E(1)=(1−K ₁ K _(DCO) K _(S)),E(0)=(1−K ₁ K _(DCO) K _(S)),ΔF.

By measuring E(1) and taking into account the fact that E(0) is equal to the change in setting, the adaptation module may compute the gain K_(DCO) by:

$K_{DCO} = {\frac{\left( {1 - \frac{E(1)}{\Delta \; F}} \right)}{K_{I}K_{S}}.}$

It is to be noted that in established operating regime, the gain K₁ is known by the adaptation module 60 (since it is generated and controlled by that module as described below). A fixed initialization value may furthermore be provided. As regards the gain K_(S) of the sensor 16, this is constant and may thus be considered as a fixed value of the system, stored for example at the adaptation module 16.

The gain K_(DCO) of the oscillator 14 is thus computed on the basis of the measurement of the input signal E(1) at a frequency jump, without opening the feedback control/regulation loop, and without having to take two measurement points.

It is noted that the above also applies when the change in setting is not a step, taking into account the particular successive values of the frequency setting.

Several measurement points may moreover be used. In that case it is then a matter of minimizing a quadratic criterion which depends on the gain K), the other parameters K₁ and K_(S) being considered to be known. A non-linear programming method may for example be implemented, as described in the work “Practical methods of optimization”, R. Fletcher, 2^(nd) edition, Wiley, ISBN 13: 978 0 471 91547 8. A least squares error method may also be implemented, which is non-optimal in this case since the problem is not linear in K), but for which the result will be entirely satisfactory if the hypothesis is made that the noise level is low.

Whatever the determination technique used, it is possible to determine, thanks to the knowledge of the gain of the oscillator 14, the gain K₁ to use at the time of the following jump to obtain a particular shape for the response as follows.

By considering the equations reviewed above, it is found that the pole a of the closed loop system is written: α=1−K₁K_(DCO)K_(S). Yet this pole is directly linked to the shape of the desired response, that is to say to the response time, for example at 5%, and to the transient shape of the temporal response (see on this subject the work “Analyse des Systèmes linéaires”, (a translation of this French title being “Analysis of non-linear systems”), under the direction of Ph. de Larminat, collection I2C, Hermes, ISBN 2-7462-0491-6).

It is provided to use predetermined values for the pole a , that are characteristic of the response shape, here a predetermined value ap for the positive setting jumps and a predetermined value α_(N) for the negative setting jumps (the differentiation between positive jump and negative jump being useful for the reasons already set out above).

Thus, when the adaptation module 60 detects a positive setting jump F_(set), it actuates the controller 12 to use a gain

${K_{I} = \frac{1 - \alpha_{P}}{K_{DCO}K_{S}}};$

on the other hand, when the adaptation module 60 detects a negative setting jump F_(set), it actuates the controller 12 to use a gain

$K_{I} = {\frac{1 - \alpha_{N}}{K_{DCO}K_{S}}.}$

It is noted that, in both cases, the value of the gain K_(DCO) used is that determined as indicated above by measurement at the previous jump (a default value may naturally be used if no measurement has been made previously, for example on initialization of the process).

The foregoing embodiments are merely possible examples of implementation of the invention, which is not limited thereto.

For example, the determination of the oscillator gain K_(DCO) by measurement, presented with reference to FIG. 6, could be used in the context of the embodiment of FIG. 4, which would make it possible to vary the value U₀ according to the gain K_(DCO) determined (the value U₀ chosen depending in particular on the oscillator gain K_(DCO) as indicated above). 

1. A supply device for supplying an electronic circuit with a clock signal having a clock frequency, the device comprising: a frequency actuator that generates the clock signal according to a frequency setting using a regulation mechanism; and a control module that selectively applies a first frequency setting or a second frequency setting higher than the first setting to the frequency actuator; wherein an adaptation module modifies the regulation mechanism according to the applied setting.
 2. A supply device according to claim 1, wherein the adaptation module modifies the regulation mechanism such that a response time of the frequency actuator increases or decreases respectively depending on whether the applied setting increases or decreases.
 3. A supply device according to claim 1, wherein the frequency actuator comprises a controller that receives an error signal obtained by a difference between the frequency setting and a measured frequency of the clock signal.
 4. A supply device according to claim 3, wherein the frequency actuator comprises an oscillator controlled by a control signal generated by the controller, and the oscillator generates the clock signal.
 5. A supply device according to claim 4, wherein the adaptation module comprises a means for determining a gain of the oscillator by measurement of at least one value involved in the regulation mechanism and the adaptation module is designed to modify the regulation mechanism according to the determined gain.
 6. A supply device according to claim 5, wherein the controller applies a gain to the error signal and the adaptation module controls the gain applied by the controller according to the gain of the oscillator.
 7. A supply device according to claim 3, wherein the adaptation module modifies an operating parameter of the controller.
 8. A supply device according to one of claim 3, wherein the controller applies a gain to the error signal.
 9. A supply device according to claim 8, wherein the adaptation module controls the gain applied to the error signal.
 10. A supply device according to claim 9, wherein a selector controlled by the adaptation module selectively applies the error signal to a selected multiplier from among a plurality of multipliers.
 11. A supply device according to claim 10, wherein the controller comprises a memory that stores a control value and the adaptation module stores in the memory a predetermined value on detection of a setting jump.
 12. A device according to claim 1, further comprising a voltage actuator that generates a voltage according to a voltage setting, adapted to the frequency setting, on application of the frequency setting to the frequency actuator. 